package UDP.UDP6;

import java.awt.dnd.DropTarget;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;

public class UdpServer {

    private DatagramSocket socket;

    public UdpServer(int port) throws SocketException {
        this.socket = new DatagramSocket(port);
    }

    public void start() throws IOException {
        System.out.println("服务器上线~");
        while(true) {
            //1.从客户端获取请求并解析
            DatagramPacket requestPacket = new DatagramPacket(new byte[4096], 4096);
            socket.receive(requestPacket);
            String request = new String(requestPacket.getData(), 0, requestPacket.getLength());
            //2.根据请求计算响应(这是一个回显服务器)
            String response = process(request);
            //3.封装响应并发送给服务器
            DatagramPacket responsePacket = new DatagramPacket(response.getBytes(),
                    response.getBytes().length, requestPacket.getSocketAddress());
            socket.send(responsePacket);
            //4.打印日志
            System.out.printf("[%s:%d] req: %s, resp: %s\n", requestPacket.getAddress().toString(), requestPacket.getPort(),
                    request, response);
        }
    }

    private String process(String request) {
        return request;
    }

    public static void main(String[] args) throws IOException {
        UdpServer udpServer = new UdpServer(8080);
        udpServer.start();
    }

}
